Assessment of Knowledge on Metal Trace Element Concentrations and Metallothionein Biomarkers in Cetaceans

Cetaceans are recognized as bioindicators of pollution in oceans. These marine mammals are final trophic chain consumers and easily accumulate pollutants. For example, metals are abundant in oceans and commonly found in the cetacean tissues. Metallothioneins (MTs) are small non-enzyme proteins involved in metal cell regulation and are essential in many cellular processes (cell proliferation, redox balance, etc.). Thus, the MT levels and the concentrations of metals in cetacean tissue are positively correlated. Four types of metallothioneins (MT1, 2, 3, and 4) are found in mammals, which may have a distinct expression in tissues. Surprisingly, only a few genes or mRNA-encoding metallothioneins are characterized in cetaceans; molecular studies are focused on MT quantification, using biochemical methods. Thus, we characterized, in transcriptomic and genomic data, more than 200 complete sequences of metallothioneins (mt1, 2, 3, and 4) in cetacean species to study their structural variability and to propose to the scientific research community Mt genes dataset to develop in future molecular approaches which will study the four types of metallothioneins in diversified organs (brain, gonad, intestine, kidney, stomach, etc.).Fil: Leignel, Vincent. Le Mans Université.; FranciaFil: Pillot, Louis. Le Mans Université.; FranciaFil: Gerpe, Marcela Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Caurant, Florence. La Rochelle University; Franci

Molecular Systematics of the Deep-Sea Hydrothermal Vent Endemic Brachyuran Family Bythograeidae: A Comparison of Three Bayesian Species Tree Methods

Brachyuran crabs of the family Bythograeidae are endemic to deep-sea hydrothermal vents and represent one of the most successful groups of macroinvertebrates that have colonized this extreme environment. Occurring worldwide, the family includes six genera (Allograea, Austinograea, Bythograea, Cyanagraea, Gandalfus, and Segonzacia) and fourteen formally described species. To investigate their evolutionary relationships, we conducted Maximum Likelihood and Bayesian molecular phylogenetic analyses, based on DNA sequences from fragments of three mitochondrial genes (16S rDNA, Cytochrome oxidase I, and Cytochrome b) and three nuclear genes (28S rDNA, the sodium–potassium ATPase a-subunit ‘NaK’, and Histone H3A). We employed traditional concatenated (i.e., supermatrix) phylogenetic methods, as well as three recently developed Bayesian multilocus methods aimed at inferring species trees from potentially discordant gene trees. We found strong support for two main clades within Bythograeidae: one comprising the members of the genus Bythograea; and the other comprising the remaining genera. Relationships within each of these two clades were partially resolved. We compare our results with an earlier hypothesis on the phylogenetic relationships among bythograeid genera based on morphology. We also discuss the biogeography of the family in the light of our results. Our species tree analyses reveal differences in how each of the three methods weighs conflicting phylogenetic signal from different gene partitions and how limits on the number of outgroup taxa may affect the results

Diversité génétique et résistance aux benzimidazoles chez ""Teladorsagia circumcincta" (Nematoda, Trichostrongylidea) parasite de petits ruminants

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Metallothionein genes from hydrothermal crabs (Bythograeidae, Decapoda): Characterization, sequence analysis, gene expression and comparison with coastal crabs

International audienceHydrothermal vent conditions can alter DNA and hydrothermal organisms may develop detoxification mechanisms and/or genetic adaptations. Hydrothermal vent animals notably synthesize a high quantity of metallothioneins (MT). Recent studies have revealed that the levels of MT within hydrothermal crustacean tissues are higher than those found in other vent animals. To improve our understanding of the environmental impacts exerted on the vent organisms, we characterized the metallothioneins (cDNA and Mt genes) of several members of the Bythograeidae (Bythograea thermydron, Cyanagraea praedator and Segonzacia mesatlantica) which is the only endemic hydrothermal crab family. In comparison, the isolation of metallothionein cDNA was also carried out in several coastal crab families. The results showed that the hydrothermal crabs possess Mt composed of three exons and two introns presenting conserved splicing signals. The cDNA sequences isolated from distinct crabs showed multiple substitutions. In spite of the unique environmental conditions, the protein sequence analysis revealed no specific amino acid residue for the MT of the three hydrothermal crabs. However, gene expression analysis performed by real-time PCR based on S. mesatlantica (hydrothermal crab) compared to Pachygrapsus marmoratus (coastal crab) confirmed the higher metallothionein induction in hydrothermal crabs suggested by others authors

Identification of new subgroup of HSP70 in Bythograeidae (hydrothermal crabs) and Xanthidae

International audienceCrabs of the Bythograeidae family (Crustacea: Brachyura: Bythogreoidea) are the only endemic crab family living in hydrothermal fields. The hydrothermal environment is characterized by unique ecological parameters, such as the high temperature gradient around the hydrothermal chimney (2-350 °C), a fluid environment containing high levels of metals and numerous gases. The 70-kDa Heat Shock Protein (HSP70) group is the most-studied HSP, because it is ubiquitous, and a strong positive correlation has been found between the amounts of HSP70 produced in response to stress, and the ability of the organism to withstand stressful conditions. The 70-kDa heat shock protein genes from Bythograeids (species analyzed: Bythograea thermydron, Cyanagraea praedator and Segonzacia mesatlantica) were characterized. Our results revealed that Bythograeidae possess genes which are similar with those present in Xanthids (coastal crabs). The deduced protein sequences displayed motifs distinct from those in the other crustacean HSC70/HSP70s available in the databases. Phylogenetic analysis showed that these members of HSP70 family identified in Bythograeidae and Xanthidae constitute a new subgroup within this family

Alternation of anthelmintic treatments: A molecular evaluation for benzimidazole resistance in nematodes

International audienceThe evolution of benzimidazoles (BZ) resistance in Teladorsagia circumcincta was investigated in a controlled trial with lambs, submitted to different treatment regimens. Four paddocks were seeded with a T. circumcincta strain constituted by 25% of BZ-resistant nematodes. Ten permanent lambs were allocated to each paddock, from April to November in order to renew the contamination of pasture. Monthly, three tracer lambs were allocated in each paddock. BZ-resistant nematode frequency was determined (PCR diagnosis). The faecal egg count reduction test (permanent lambs) and the number of nematodes in lambs were also determined (permanent and tracer lambs). Four different regimens of treatments were performed: control, levamisole (a non-BZ drug), fenbendazole (a BZ drug), and an alternation of levamisole and fenbendazole every second treatment. The same protocol was repeated on two consecutive grazing seasons, increasing the number of treatments (3 in first year and 5 in second year). The proportions of BZ-resistant nematodes did not change during all the study in both the control and the levamisole paddocks, supporting an equal global fitness of BZ-resistant and susceptible nematodes. Thus, no reversion of BZ resistance is to be expected. In the alternated drug group and in the BZ treated group, BZ-resistant nematodes increased from 25% to 47% and to 78%, respectively. BZ resistance increased proportionally to the selective pressure (number of BZ treatments). The drug alternation is not a good solution to delay importantly the evolution of resistance when more than 25% of nematodes are BZ-resistant. This study is the first evaluation of BZ-resistance evolution (using individual genotyping) in controlled conditions. It showed that when a monogenic anthelmintic resistance is established at 25% in a sexually reproducing nematode population, it seems to be impossible to prevent its increase even when using limited number of BZ treatments

Alternation of anthelmintic treatments: A molecular evaluation for benzimidazole resistance in nematodes

International audienceThe evolution of benzimidazoles (BZ) resistance in Teladorsagia circumcincta was investigated in a controlled trial with lambs, submitted to different treatment regimens. Four paddocks were seeded with a T. circumcincta strain constituted by 25% of BZ-resistant nematodes. Ten permanent lambs were allocated to each paddock, from April to November in order to renew the contamination of pasture. Monthly, three tracer lambs were allocated in each paddock. BZ-resistant nematode frequency was determined (PCR diagnosis). The faecal egg count reduction test (permanent lambs) and the number of nematodes in lambs were also determined (permanent and tracer lambs). Four different regimens of treatments were performed: control, levamisole (a non-BZ drug), fenbendazole (a BZ drug), and an alternation of levamisole and fenbendazole every second treatment. The same protocol was repeated on two consecutive grazing seasons, increasing the number of treatments (3 in first year and 5 in second year). The proportions of BZ-resistant nematodes did not change during all the study in both the control and the levamisole paddocks, supporting an equal global fitness of BZ-resistant and susceptible nematodes. Thus, no reversion of BZ resistance is to be expected. In the alternated drug group and in the BZ treated group, BZ-resistant nematodes increased from 25% to 47% and to 78%, respectively. BZ resistance increased proportionally to the selective pressure (number of BZ treatments). The drug alternation is not a good solution to delay importantly the evolution of resistance when more than 25% of nematodes are BZ-resistant. This study is the first evaluation of BZ-resistance evolution (using individual genotyping) in controlled conditions. It showed that when a monogenic anthelmintic resistance is established at 25% in a sexually reproducing nematode population, it seems to be impossible to prevent its increase even when using limited number of BZ treatments

Aquat Ecol

Ocean and sea areas should be named following agreed international standards. Here, the standards and specifications set by the International Hydrographic Organization (IHO 1953) apply; therefore, the name of the study area, “Arabian Gulf” in the original version should be replaced with “Persian Gulf” in Table 1 and in the text under “Aluminium in seawater”

Aquat Ecol

Aluminium (Al) is a common chemical element released into the aquatic environment from the Earth’s crust and many anthropogenic activities. It may be present in various dissolved and precipitated forms [Al3+, AlOH2+, Al(OH)2+, Al(OH)03, Al(OH)4−, etc.], which are potentially toxic for organisms. This review summarizes information about the concentrations of Al detected in aquatic ecosystems and its effects on both freshwater and marine organisms (such as growth disturbance, reproduction, and respiration alterations). As the chemistry of Al is different in freshwater and marine systems, we discuss the behaviour of aluminium and its effects on marine or freshwater fauna. Therefore, the solubility of Al, as other metals, is highly pH dependent, which increases when pH decreases. We are assuming that ocean acidification, linked to climate change, would affect the Al bioavailability in the aquatic environment, which may increase its ecotoxicological effects on semi-closed (Bays, Mediterranean Sea, etc.) or closed (lakes, etc.) aquatic ecosystems